There is increased use of systems that are remotely monitored. These systems may only occasionally be visited by human operators. Such systems may be remote in their location, or may be in everyday situations, for example in households, commercial premises, or urban or town environments.
The reasons these systems may rarely see human operators is because they may be numerous in number and therefore the cost of regular visits may be too high, or may be too remote to regularly visit. The systems themselves tend to be stable and will easily run for long periods of time with no need for a human operator on site.
Such systems however, because they may be in dense population areas may be the target of attempted theft, vandalism or other abuse which may compromise the system itself, or at least the cabinet, components, for example key pad or similar the system and equipment is contained in. The lack of regular human visits makes detection of such tampering difficult.
Examples of such systems are household and commercial power meters. These can now be easily monitored from the central control of the power company and thus there is no need to visit such equipment to take meter readings as there has been in the past. Moreover, there is a need to ensure such meters are not tampered with due to the cost of such meters and also the loss of revenue if such meters do not read correctly.
There may also be systems that are regularly visited, but their equipment or content may be mission critical (for example traffic light systems), of high value (for example currency vending machines), or that otherwise require confidence in their integrity and security (for example EFTPOS payment machines.
Tamper detection is also valuable for a computer or electronics suite. For example, it may allow an alert to occur if a person attempts to gain access to the internal units or remove device components. Equipment that has key pads, security card readers, or credit card and EFTPOS machine readers can often be tampered with to remove and replace the content with the tamperer's own equipment. This, for example, would direct funds to the tamperer's account instead of the correct account. Other tampering may involve insertion of information scanning systems to allow capture of a user's information, for example security keypad entry, credit card or EFTPOS card details.
There is also a need for a device which can detect the loosening of, for example, fasteners or other components relative to each other. Such loosening may occur due to tampering, but may also occur due to general wear and tear, vibration and movement, and the weather.
An example of a prior art solution is that found in U.S. Pat. No. 6,774,807 of Lehfeldt et al. This discloses a fastener that utilises a magnetic switch or micro-switch in the fastener or against the fastener periphery that activates when the fastener is turned through a certain angle. These switches are actuated by a mechanical system that must be in close proximity to the fastener, or utilise a magnetic pickup and associated components. As such they require extra systems and components and specially designed and shaped fasteners.
In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art.
It is therefore an object of the present invention to provide an improved tamper evident system, or to overcome the above shortcomings or address the above desiderata, or to at least provide the public with a useful choice.